Three-roll mill for crushing sugar cane and the like



April 1943- J. D. COMPAIN 2,316,843

THREE-ROLL MILL FOR CRUSHING SUGAR CANE AND THE LIKE Filed March 11, 1941 2 Sheets-Sheet l April 20, 1943. J. D. COMPAIN 2,316,843

THREE-ROLL MILL FOR CRUSHING SUGAR CANE AND THE LIKE Filed March 11, 1941 2 Sheets-Sheet 2 Z52y9/2z' Patented Apr. 20, 1943 THREE-ROLL MILL FOR CRUSHING SUGAR CANE AND THE LIKE J ernimo Diaz Compain, Central Senado, Cuba Application March l1, 1941, Serial No. 382,828

I In Cuba December 17, 1940 12 Claims.

This invention relates to three-roll mills for crushing sugar cane and the like; and it comprises in combination a feed roll, an upper roll, a discharge roll andfa turn plate, the feed roll being adjustably mounted in a stationary housing while the upper and discharge rolls are mounted in a tiltable housing pivoted On a stationary shaft running parallel to the axes of the three rolls,

. said shaft being preferably positioned substantially on a line joining the axes-of the top roll and the discharge roll substantially midway between the two axes; all as more fully hereinafter set forth and as claimed.

The three-roll mill provided with a turn plate has been widely used in the extraction of juice from sugar cane. Such mills are equipped with what is called a feed roll, a top roll and a discharge roll. The space between the top roll and the feed roll forms what is known as the feed opening or first pass or compression while the space between the top roll and the discharge roll is termed the discharge openingor second pass or compressio In such mills it is always necessary to provide at least one movable roll in order that the mill may accommodate itself to variations in the thickness of the cane or bagasse blanket which is passed therethrough. One of the more common types of these mills is provided with a vertically movable top roll while the feed roll and the discharge roll are stationary. When the top roll of this mill rises it increases the width of both the feed opening and the discharge opening simultaneously. This is, of course, a distinct disadvantage since the thickness of the bagasse blanket seldom varies equally at the two openings. If the opening at either point is larger than that required, the efficiency of the extraction is reduced. Attempts have been made to overcome this difficulty by the use of an independently movable feed or discharge roll but this provision has introduced a new difficulty involving the correct setting of the turn plate with respect to the rolls. The requirements of this setting are very strict.

It has been recognized by all the authorities on mill design that the space between the turn plate and the surface of the top roll should increase from the front end of the turn plate to its rear end in order that the friction caused by the flow of materials along this plate should be a minimum. This rule is expressed mathematically as c' b a wherein it represents the distance from the front edge of the turn plate to the surface of the top roll, 1) represents the distance from the center of the turn plate to the and simultaneously surface of the top roll and 0 represents the distance from the rear edge of the turn plate to the surface of the top roll. The distances a, b and c must be correctly adjusted, of course, in order that the mill should operate correctly.

The adjustment of the distance between the feed roll and the top roll, that is, the feed opening or inlet E, the adjustment of the distance between the top roll and the discharge roll, that is, the discharge opening or outlet S, and the distance between the rear edge of the turn plate and the discharge roll, usually designated by d, are of equal importance in the operation of the mill. For normal operating conditions and for '7 foot rolls having diameters of 3'7 inches, the following adjustment of these parts may be given as an average: E=l", S=%", a=2E or 2", b=2E+ A" or 2 c=2E+ /2" or 2 /2, and d=%" to It will be noted that these dimensions follow the rule c b a.

During the operation of the mill the distances E and S vary with the thickness of the bagasse blanket and these distances frequently increase to 1" or more above the values given above. The displacements of the movable rolls are, of course, very irregular but it is important for best operation of the mill that these displacements should not greatly change the relative distances between the rolls and the turn plate and, more especially, that the above rule should be followed regardless of the displacements. In most of the mills in which two movable rolls have been provided this provision is not made.

I have found a simple construction embodying two movable rolls in which the above rule is followed regardless of the displacements of the movable rolls and also wherein the widths of the inlet and of the outlet may vary independently during the operation of the mill. In this construction I employ a stationary but adjustable feed roll. The top and discharge rolls are mounted in a pivoted housing, the pivot being substantially on the line joining the axes of these rolls and being substantially midway between them. The housing is provided, with a hydraulic ram or other means bearing against the lower end of the housing for pressing the upper end ofthe housing and consequently the top roll towards the feed roll, while a second hydraulic ram or other means is provided to press the top roll against the discharge roll. The discharge roll is adjustably mounted in the pivoted housing. The turn 'plate is mounted stationary but is adjustable and this is positioned with its front edge substantially bearing against the feed roll in the usual manner.

. ceive the bolts 28.

The result is a mill which is highly flexible with respect to adjustment and in which he pres sures at the inlet and at the outlet are maintained independently, while the mill always conforms to the above mentioned rule for the spacing between the turn plate and the top roll.

My invention can be explained in more detail by reference to the accompanying drawings in which the figures show, more or less diagram matically, a preferred embodiment of this invention. In this showing: 7

Fig. 1 is an elevation of my mill,

Fig. 2 is a partial cross section taken along the line 2-2 of Fig. 1, showing the roll mountings at one end of the pivoted housing, while Fig. 3 is a diagram showing the relative positions of the rolls during displacements due to differences in the thickness of the bagasse blanket.

In the various figures like parts are represented by like reference numerals. Referring to Fig. 1, my mill is provided with a base plate or stationary mill housing I on which the various parts are mounted. Side plates or brackets 2, which are integral with the base plate, serve to support the feed roll 3 and the pivot I of the mill housing 4 which in turn supports'the top roll 5 and the discharge roll Ii.

The side plates are provided with cut out portions 9 for receiving the journals 8 of feed roll 3,

housing 4 is supported by the ears or lugs I3 formed in the side plates 2 of the stationary mill housing. The cars on each end of the rolls are bifurcated, as shown in Fig. 2, to receive the center lug I4 of the pivoted housing 4, these elements being bored to receive the pivot or hingepin I5. The opposite faces of the mill housing 4 are cut away, as at I6, to receive the ears I3 and to provide sufiicient clearance for the required pivotal motion of the housing.

The journals of the discharge roll Ii are mounted in adjustable bearing blocks I1, these blocks being slidable between the guides I8. Adjustment is provided for by means of the sliding, tapered blocks I8, which bear against the correspondingly tapered lower edges of, the bearing The pressure required for thesecond pass or compression at the discharge opening of the mill is, of course, supplied by the hydraulic ram 25. The block 3| serves as-meansfor limiting the pivotal motion of the mill housing to prevent the top roll from completely closing the feed opening, while block 32 limits the pivotal motion in the opposite direction. The turn plate is shown at 33, this being mounted on means generally shown at 34. This turn plate is adjustably mounted in such position that its front edge bears against the feed roll. Its rear edge approaches the surface of the discharge roll but sufficient clearance is left at this point to provide for discharge of the juices expressed in the final pass between the discharge and the top rolls. 7

During the operation of the mm the feed roll remains fixed in position while the discharge roll pivots about the hinge pin I5 in accordance with the pivotal movement of the mill housing 4. The top roll, of course, pivots aboutthe same hinge pins but this roll also slides in the housing towards or away from the discharge roll, in accordance with the pressure exerted by the hydraulic ram 25. The pressures at the two passes or compressions are thus maintained independently,

these insuring proper operation of the mill regardless of the instantaneous changes in thickness of the bagasse blanket.

The displacements of the rolls during operation of the mill are illustrated more or less diagrammatically in Fig. 3. The axes of the rolls 5 and 6 at any instant are always located along a line passing through the pivot point I5, but the distance of the top roll from this pivot point may vary along this line, owing to the operation of the hydraulic ram 25. The distances from the surface of the top roll to the front edge, to the center and to the rear edge of the turn plate are represented in the figure by the letters a, b and 0, respectively. As shown in the figure c b a in the original or full line position of the three rolls, which have centers at the points 35, 38 and 31, respectively. The position of the turn plate is adjusted so that the arc, along its upper surface, has a center at the point 31, at a distance R from the turn plate surface. The feed opening is represented on the figure by E and the discharge opening by S. l

The dotted lines show the corresponding positions of the rolls during operation of the mill when the feed opening is increased by 1 inch J and the discharge opening is simultaneously increased by the same amount. These positions blocks, the sliding blocks being threaded to re- The discharge roll by these means can be adjusted in the mill housing 4 towards or away from the top roll 5.

The journal of the top roll is mounted between two bearing or pressure blocks 2| and. 22. A bearing plate 23 rests against the upper face of bearing block 2I and the piston 24 of a hydraulic ram 25 bears against this plate. The bearing blocks 2I and 22 are slidable between the guides 25 and 21 and roller bearings 28 are provided to reduce the friction along "the upper guide'at the point where the pressure between the rolls 3 and 5 is applied. This pressure is produced by means of the lower hydraulic rams 29 and 30 which bear against the lower part of the mill housing and produce the pressure required in the first pass or compression at the feed opening of the mill. 7

are located by first drawing the are 38 from the pivot point I5, with a radius equal to s-l-radius of roll 5+1 inch. Then from the center 35 of the feed roll an arc is struck having a radius equal to radius of roll 3+radius of roll 5+E+1 inch. This are intersects are 38 at the point 38,

which represents the center of roll 5 in its new position. Roll 5 in .its new position is indicated by dotted line 5'. It is evidentfrom inspection of the figure that the new distances from the surface of the roll 5 to the front edge, the center and the rear edge of the turn plate, which are represented on the figure by the letters a, b and c, are such that the rule c' b a. still holds and that therefore the mill'will operate correctly in the new positions of the rolls.

The new center 48 of roll 8 is located by first drawing an are passing through center ,3! from the pivot point I5 and then finding the intersection point of this are withan extended line drawn through points 38 and I5. 'It will be noted that roll 6 is displaced slightly towards the rear edge of the turn plate, i. e. that the distance between the surface of the discharge roll and the turn plate, indicated at d on the figure is reduced slightly. This distance d, in the case of rolls of 7 foot length having diameters of 37 inches, should be within the range of about to inch and it is evident from the figure that the new distance d is well within these limits. It is an advantage that this distance d is reduced during operation of the mill, rather than being increased, for the reason that this distance tends to increase in use due to the wear on the turn plate. This wear usually necessitates adjustment of the position of the turn plate once a week during grinding season.

It is evident from the above discussion of Fig. 3 that my new mill satisfies the uniform rule of mill operation and that it supplies pressures at the two passes or compressions which are applied independently. It is further evident that the mill is equally effective in the crushing of heavy cane as in the pressing of highly disintegrated materials such as cachaza or heavy muds from .the vacuum filters. These results are accomplished by the use of only one slidable roll, namely the top roll. It is believed that this is the first time that this result has been accomplished in a practical manner.

While I have described what I consider to be the best embodiments of this invention it is evident that various modifications may be made in the specific constructions described without departing from the purview of this invention. Thus, while I have illustrated the pivot point of the mill housing 4 as being preferably on the line joining the axes of rolls 5 and 6 and substantially midway between these rolls, the position of this pivot point may be varied to some extent from this position without affecting the operation of the mill. The most advantageous range of positions of this pivot point is within the area marked on the drawing by VTWU. This area is bounded by two horizontal lines, one being drawn through the center of the discharge roll and the other being drawn tangent to the top of the roll, also by the line connecting the axes of the top roll and of the discharge roll, and by the upper perimeter of the discharge roll between the points of intersection of this perimeter with the said two horizontal lines. If the pivot point is placed much below the area designated there is a tendency for the space between the discharge roll and the turn plate to increase in width upon pivotal movement of the housing and it is also true an additional force or a less advantageous construction would be required to press the top roll against the feed roll. I therefore prefer to locate the said pivot point at least a short distance above the axis of the discharge roll.

The type of mounting, which has been described for the several rolls and the turn plate, may be varied widely and other details of the construction can be altered. The positions of the hydraulic rams shown in the drawings can be changed, if desired. It is believed to be evident that my mill can be used in many different types of industrial pressing and crushing operations and that it is particularly adapted for the extraction of juices or liquids from absorbent materials. Other modifications of this invention which fall within the scope of the following claims will be evident to those skilled in the art.

1. A three-roll mill with two movable rolls and two passes for crushing sugar cane and the like which comprises a stationary frame, a feed roll mounted on said frame, a mill housing pivotally supported by said frame by a pivotal mounting, a top roll and a discharge roll mounted in said housing on opposite sides of said pivotal mounting and moveable about said mounting, means adapted to rotate said housing about said pivotal mounting to press said top roll against said feed roll, thereby producing pressure for the first pass of said mill, and means adapted to press the top roll against the discharge roll thereby producing an independent pressure for the second pass of said mill. 4

2. The mill of claim 1 wherein said pivotal mounting is positioned substantially on a line connecting the axes of the top roll and of the discharge roll.

3. The mill of claim 1 wherein said pivotal mounting is positioned substantially on a line connecting the axes of the top roll and of the discharge roll and substantially midway between said rolls.

4. A three-roll mill with two movable rolls and two passes for crushing sugar cane and the like which comprises a stationary frame, a feed roll mounted on said frame, a mill housing pivotally mounted on said frame, a top roll and a discharge roll mounted in said housing, the pivot of said pivotal mounting being positioned between the axes of said top roll and said discharge roll substantially on a line joining the axes of said top roll and said discharge roll, means bearing against the lower end of said mill housing for rotating the housing around said pivot in such a direction as to press said top roll towards said feed roll to supply the pressure required in the first pass of said mill and independent means for pressing the top and discharge rolls one against the other, thereby supplying pressure for the second pass of said mill.

5. The mill of claim 4 wherein the pivotal mounting is positioned substantially midway between the top and the discharge rolls.

6. A three-roll mill with two movable rolls and two passes for crushing sugar cane and the like which comprises in combination a feed roll, a top roll, a discharge roll and a turn plate, the feed roll being adjustably mounted while the top and the discharge rolls are mounted in a housing pivoted on a stationary shaft running parallel to the axes of the three rolls, said shaft being positioned between the axes of the top and the discharge rolls and substantially on a line joining said axes.

7. The mill of claim 6 wherein said shaft is positioned substantially midway between the top roll and the discharge roll.

8. A mill for crushing sugar cane and the like which comprises a top roll, a feed roll and a discharge roll, a turn plate mounted between said feed roll and said discharge roll for passing material from the space between said top roll and said feed roll to the space between said top roll and said discharge roll, a stationary mounting for said feed roll and a stationary pivot for pivotally supporting said top roll and said discharge roll, said pivot being positioned at a point substantially midway between the axes of said top roll and said discharge roll.

9. The mill of claim 8 including means for pressing said top roll towards said feed roll, independent means for pressing said top roll towards said discharge roll and means for limiting the pivotal motion of the mill housing to prevent complete closing of the feed opening between the top roll and the feed roll.

10. The mill of claim 8 wherein a hydraulic ram is provided for swinging said top roll about said pivot towards said feed roll, another hydraulic ram is provided for pressing said top roll towards said discharge roll and wherein means are provided for limiting the pivotal motion of the mill housing to prevent complete closing of the feed opening between the top roll and the feed roll.

11. A three-roll mill with two moveable rolls and two passes for crushing sugar cane and the like which comprises a feed roll, a top roll and a dischrage roll, a turn plate for transferring material crushed between the top and feed rolls to the space between said top and discharge rolls a stationary mounting for said feed roll, a housing for pivotally supporting the axes of said top roll and said discharge roll and a pivot for supporting said housing, the axis or said pivot being above the axis of said discharge roll but being positioned within the general area bounded by two horizontal lines one of which passes through the axis of said discharge roll, the other being tangent to the top surface of the discharge roll, said area being further bounded by a line joining the axes of said top and discharge rolls as well as by a line following the upper part of the perimeter of said discharge roll.

12. The mill of claim 1 wherein means are provided for limiting the pivotal motion of said mill housing to prevent complete closing 01' the feed opening between said top roll and said feed roll.

JERONIMO DIAZ COMPAIN. 

